ES2214493T3 - A TISSUE ABLATION REGULATION SYSTEM USING THE TEMPERATURE SENSORS. - Google Patents

Abstract

A system and associated method ablate body tissue using multiple emitters of ablating energy. The system and method convey ablating energy individually to each emitter in a sequence of power pulses. The system and method periodically sense temperature at each emitter and compare the sensed temperatures to a desired temperature established for all emitters to generate a signal individually for each emitter based upon the comparison. The system and method individually vary the power pulse to each emitter based upon the signal for that emitter to maintain the temperatures at all emitters essentially at the desired temperature during tissue ablation.

Description

A tissue ablation regulation system using temperature sensors.

Field of the Invention

The invention relates to systems for ablation of myocardial tissue for the treatment of conditions cardiac

Background of the invention

Doctors today make use of catheters in medical procedures to gain access to interior regions of the body and ablate designated areas of tissue. It is important for the doctor to be able to accurately locate the catheter and to control the emission of energy within the body during tissue ablation procedures.

For example, in electrophysiological therapy, it use ablation to treat heart rhythm disturbances.

During these procedures, the doctor directs the catheter through a vein or main artery to the region inside of the heart that will be treated. The doctor places an item of ablation, carried by the catheter, near the cardiac tissue that It must be ablated. The doctor directs the energy of the element of ablation in order to ablate the tissue and form an injury.

In electrophysiological therapy there is a growing need for ablation elements capable of provide lesions, in the tissues of the heart, that have Different geometries

For example, it is believed that the treatment of atrial fibrillation requires training in the tissue of the heart, long, thin lesions, in different ways curvilinear Such models of long, thin lesions require of the deployment within the heart of ablation elements flexible that have multiple ablation regions. The formation by ablation of these lesions can provide the same therapeutic benefits than complex suture models, which in currently provides the surgical procedure of labyrinths, but, without open heart invasive surgery.

As another example, it is believed that the treatment of atrial vibration and ventricular tachycardia requires the formation of relatively large and deep lesion models in the tissue of the heart. Merely provide "more electrodes large "does not meet this need. Catheters, which carry large electrodes, are difficult to introduce into the heart, and it is difficult to deploy them for intimate contact with the heart tissue However, with the distribution of this greater ablation mass, required for these electrodes, between multiple electrodes, separated, spaced apart along a Flexible body, these difficulties can be overcome.

With the elements of multiple electrodes, older and / or longer, there is a demand for more precise control of the ablation process. Ablation energy delivery is due direct to avoid incidents of tissue damage and formation of clots Ablation energy delivery must also be carefully controlled to ensure the formation of injuries uniform and continuous, without formation of hot spots and voids in the ablated tissue.

The document WO-A-93/13816 discloses an apparatus for the application of high frequency energy to the tissue designated by Medium of multiple emitters.

Brief description of the drawings

Fig. 1. is a view of a probe carrying a flexible ablation element that has multiple elements thermometers.

Fig. 2 is an enlarged view of the handle of the probe shown in Fig. 1, with separate portions and in section, showing the steering mechanism to flex the element of ablation.

Figs. 3 and 4 show the flexure of the element of ablation against the different surface contours of tissues.

Fig. 5 is a view of a terminal section of an ablation electrode element carrying a sensor element Of temperature.

Fig. 6 is a terminal section view of a ablation electrode element that carries two sensor elements Of temperature.

Fig. 7 is a view of a terminal section of an ablation electrode element that carries three elements thermometers.

Fig. 8 is a view of the side section of a flexible ablation element comprising elements of multiple rigid electrodes, showing a way to mount so minus a temperature sensor element under the elements of electrodes

Fig. 9 is a view of a side section of a flexible ablation element comprising elements of multiple rigid electrodes, showing the assembly of at least a temperature sensing element between the electrode elements adjacent.

Fig. 10 is a view of a side section of a flexible ablation element comprising multiple elements rigid ablation, showing the assembly of at least one temperature sensor element in the electrode elements.

Fig. 11 is an enlarged top view of the mounting the temperature sensor element on the rigid electrode, shown in Fig. 10.

Fig. 12A / B / C are schematic views of alternative ways to connect multiple thermocouples for use in association with an ablation element.

Fig. 13 is a side view of an element flexible ablation with multiple and multiple electrodes thermocouples, and additionally includes a reference thermocouple incorporated, exposed to blood flow.

Fig. 14A is an enlarged view of the section side of the incorporated reference thermocouple, shown in Fig. 13.

Fig. 14B is an enlarged view of the section side of an alternative embodiment of the reference thermocouple incorporated, shown in Fig. 13.

Fig. 15A is a side section view of mounting a star connection, used as a union of reference for multiple thermocouples.

Fig. 15B is the schematic representation for the star connection of the reference junction shown in Fig. 15A.

Fig. 16A is a side section view of the assembly of multiple built-in reference thermocouples.

Fig. 16B is a schematic view of multiple built-in reference thermocouples, shown in Fig. 16A.

Fig. 17 is a perspective terminal view, with separate portions and shown in its section, of a thermocouple flexible compound usable in association with an element flexible ablation.

Fig. 18 is a view of the side section of the flexible thermocouple in use in association with a flexible element of ablation.

Figs. 19 and 20 are schematic views of a system to control the application of ablation energy to multiple electrodes using inputs from multiple sensors of temperature.

Fig. 21 is a schematic flow chart that show an application of the temperature controller with feedback, shown in Figs. 19 and 20, using the control Single amplitude with charge cycle control collective

Fig. 22 is a schematic flow chart that show an application of the temperature controller with feedback, shown in Figs. 19 and 20, using the control of individual load cycle with collective control of amplitude.

Fig. 23 is a schematic flow chart that show an application of the temperature controller with feedback, shown in Figs. 19 and 20, using the control of temperature with hysteresis.

Fig. 24 is a schematic flow chart that shows an application of the temperature controller, with feedback, shown in Figs. 19 and 20, using a deactivation by variable amplitude and differential temperature.

Fig. 25 is a schematic flow chart that shows an application of the temperature controller, with feedback, shown in Figs. 19 and 20, using differential temperature deactivation.

Fig. 26 is a schematic view of a Neural network predictor that receives the temperature as input noted by multiple sensing elements in a given region of electrode and output at a predicted temperature of the region of the hottest fabric.

The invention can be carried out in several ways. without departing from its essential characteristics. The scope of the invention is defined in the appended claims, rather than in the specific description that precedes them. It is considered, by consequently, that all the realizations, that fall within the meaning and range of equivalences to the claims, are encompassed by the claims.

Description of the preferred embodiments

The present specification reveals multi electrode structures. This descriptive report also reveals tissue ablation systems and techniques, which use multiple temperature sensing elements, which include others aspects of the invention. Preferred embodiments and illustrated discuss these structures, systems, and techniques in the context of cardiac catheter ablation. This is because these structures, systems and techniques are well suited for use in the field of cardiac ablation.

Even more, it should be appreciated that the present invention is applicable for use in other applications of tissue ablation. For example, several aspects of the invention have application in tissue ablation procedures in prostate, brain, gallbladder, uterus, and other regions of the body, using systems that are not necessarily catheter based.

I. Flexible ablation elements

Fig. 1 shows a flexible element of 10 ablation to perform injuries inside the heart.

Element 10 is carried at the distal end of a catheter body 12 of an ablation probe 14. The probe ablation 14 includes a handle 16 to the proximal end of the body of the catheter 12. The handle 16 and the body of catheter 12 carry a steering mechanism 18 to selectively bend or flex the ablation element 10 in two opposite directions, as shown the arrows in Fig. 1.

The steering mechanism 18 may vary. In the illustrated embodiment (see Fig. 2), the steering mechanism 18 includes a rotating cam wheel 20 with a steering lever external 22 (see Fig. 1). As Fig. 2 shows, the wheel of the cam 20 holds the right and left proximal ends of the conductor wires 24. The wires 24 pass through the body of catheter 12 and connect with the left and right sides of a wire or spring 26, conformable, elastic (best shown in the Fig. 5, 6, and 7), enclosed within a tube 28 within a ablation element 10.

Additional details of this and others are shown types of steering mechanisms for ablation element 10 in Lundquist and Thompson, U.S. Pat. No. 5,254,088.

As Fig. 1 shows, the forward movement of the steering lever 22 flexes or bends down the ablation element 10. The subsequent movement of the lever director 22, flexes or hunches up, the element of ablation 10.

Several access techniques can be used to insert the probe 14 into the desired region of the heart. By example, enter the right atrium, the doctor can direct the probe 14 through a conventional vascular introducer by the Femoral vein. For entry into the left atrium, the doctor can direct probe 14 through a vascular introducer conventional retrograde through the aortic valves and mitral

Alternatively, the doctor can use the system of delivery, shown in patent application No. 08 / 033,641, filed on March 16, 1993, and entitled "Systems and methods using guide sheaths to introduce, deploy and stabilize probes of mapping and cardiac ablation. "

The doctor can verify that there is a contact intimate between element 10 and heart tissue using techniques Conventional steps and sensor. Once the doctor establishes intimate contact with the tissue in the desired region of the heart, applies the ablation energy to element 10. The type of energy of ablation delivered to item 10 may vary. In the realization illustrated and preferred, element 10 emits energy radio frequency electromagnetic.

The flexible ablation element 10 can set up in several ways. Figs. 3 and 4 show a preferred application. In this embodiment, element 10 includes 30 elements of multiple electrodes, generally rigid, placed in a segmented relationship spaced apart, in a flexible body 32.

The flexible body 32 is made of a material polymeric, electrically non-conductive, such as polyethylene or polyurethane. Segmented electrodes 30 comprise rings solids of conductive material, such as platinum. Electrode rings 30 are snapped onto body 32. Portions flexible body 32, between rings 30, comprise regions not electrically conductive. The segmented electrodes 30 are electrically couple the wires (not shown) to direct the energy of ablation to them.

The body 32 can flex between electrodes 30, spaced apart, to carry electrode 30 in intimate contact on a curvilinear surface of the wall of the heart, if the heart appears hunched out (as shown Fig. 3) or if it bends toward the center (as shown in Fig. 4). The number of electrode segments 30 and the space between them may vary, depending on the particular objectives of the procedure of ablation. Similarly, the dimensions of the segments individual electrodes 30 and the underlying body 32 also They may vary for the same reason.

Generally speaking, the electrode structure segmented element 10 is well prepared to create models of continuous, long and thin lesions, provided that electrode segments 30 are spaced sufficiently together and close, and the ablation energy be simultaneously applied to adjacent electrode segments 30. Continuous models of injuries result when adjacent electrode segments 30 are space separately no further than about 2.5 times the electrode segment diameter. However, the energy of ablation can be applied selectively to one or a selected group individually of electrode segments, when it is desired to vary additionally the size and characteristics of the model of injuries

In the segmented electrode structure of the element 10, the diameter of the electrode segments 30, being under flexible body 32, it can vary from about 4 fr. at about 10 fr. Using the rigid electrode segments 30, The minimum diameter is approximately 1.35 mm.

It has been found that adjacent segments of electrode 30, which have lengths less than about 2 mm, do not consistently form continuous injury models desired. Using the rigid electrode segment 30, the length of each of the electrode segments may vary from approximately 2 mm to approximately 10 mm. The use of multiple rigid electrode segments, each larger than approximately 10 mm has adverse effects on flexibility global element 10 (1).

In a representative electrode structure segmented, flexible body 32 is approximately 1.35 mm of diameter. The body carries electrode segments 30, in which each has a length of 3 mm. When eight segments of electrode 30 are present and simultaneously activated with 100 watts of radio frequency energy for approximately 60 seconds, the lesion model is long and thin, measuring approximately 5 cm in length and approximately 5 mm of thickness. The depth of the lesion model is approximately 3 mm, the one that is most appropriate to create the required transmural lesion (the thickness of the atrial wall is generally less than 3 mm).

The shape of the injury model created by the flexible ablation element 10 can be controlled by bending the body from rectum to curvilinear. As already explained, the body can go remotely to flex it in the desired way, or you can have a fixed memory, preforming it in the desired way, also from straight to curvilinear.

The flexible ablation element 10 can also be used to form models of larger and deeper lesions, forming the support body 32 in the form of a circle or a spiral to increase electrode density per given area of tissue. This diagonal space and / or intimate closed diametral face of electrode segments in such structures, coupled with the simultaneous emission of ablation energy by segment of electrodes, significantly concentrates the energy distribution of ablation. The electrode segments 30 provide an effect Additive calorific causes injuries that span segments of electrodes, which are diagonally close and / or diametrically faced. Extended injuries thus create injury models large and deep in the region of tissues that element 10 contact

In the preferred and illustrated embodiments, the flexible ablation element 10 carries at least two elements 80 temperature sensors. Multiple sensor elements of temperature 80 measure temperatures along the entire length  of item 10.

In this configuration, the sensor elements 80 they are preferably located in an aligned relationship along one side of each segmented electrode 30, as shown in Fig. 3 and Four.

The body 32 preferably carries a marker fluoroscopic (such as line 82 shown in Figs. 3 and 4) to orientation purposes. Stripe 82 can be made of a material, like tungsten or barium sulfate that are extruded outward into the pipe 12. The extruded line can be fully inserted by the pipe or it can be extruded in the outer diameter, making the pipe visible to the eye. Fig. 5 shows a marker on the wall of the pipe 12. An alternative embodiment is a opaque fluoroscopy wire such as platinum or gold that can Extrude into the pipe wall. Still in another embodiment, a marker sticks to the internal diameter of the pipe during its manufacturing.

The sensor elements 80 may be in the same side of fluoroscopic marker 82 (as shown in Fig. 3 and 4), or on the opposite side, as long as the doctor is aware of their relative position. Aided by the marker 82, the doctor guides the element 10 (1) so that the elements 80 temperature sensors come into contact with the tissue designated.

Alternatively, or in combination with the fluoroscopic marker 82, the sensor elements 80 can consistently located inside or outside the surface of element 10 (1) when hunched in a given direction, or down. For example, as Fig. 3 shows, when element 10 (1) bends over and extends towards below, the sensor elements 80 are exposed on the surface  inside of element 10 (1). As Fig. 4 shows, when the element 10 (1) bends up, sensor elements 80 they are exposed outside on the surface of element 10 (one).

Each electrode segment 30 can carry more than a single temperature sensor element 80. As shown in Fig. 5 to 7, each electrode segment 30 can carry one, two, three, or more 80 temperature sensing elements, spaced in the form of circumference. The presence of multiple sensor elements of temperature 80 in a single electrode segment 30 gives it higher latitude to the doctor to position the ablation element 10, while still providing supervision over the temperature.

As Fig. 5 shows, a thin layer 56, thermally and electrically insulating, can be applied to the side of the sensor electrode 30, simple segmented, opposite the sensor element of temperature 80, which, in use, is exposed to blood flow. The layer 56 can be applied, for example, by brushing on an adhesive UV type or over material poly (tetrafluoro-ethylene) (PTFE).

As Fig. 6 shows, mask layer 56 is located between the two sensors 80 on the segmented electrode 30 of two sensors. The mask layer 56 minimizes the effects convective blood flow refrigerators in the regions of your  electrode segment 80 exposed to it. The condition of 80 detected tissue temperature is with this more exact. When more than two temperature sensors 80 are used in a segment given electrode 30, masking becomes less advisable, since  that the effective surface of the electrode segment 30 is reduced available for contact with the tissue and its ablation.

The temperature sensing elements 80 can Understand thermistors or thermocouples.

The sensor element or elements 80 may lean forward or near the segmented electrodes 30 of Several ways.

For example, as shown in Fig. 8, each of the sensor elements 80 are sandwiched between the outside of the body flexible 32 and the bottom of the rigid electrode segment associated 30. In the illustrated embodiment, the sensor element 80 It includes thermistors. The body 32 is flexible enough as to fit the sensor elements 80 under the segment of electrode 30. The plastic memory of the body 32 maintains the sufficient pressure against the temperature sensor element 80 as to establish a good thermal conductive contact between him and the electrode segment 30.

In an alternative embodiment (as the Fig. 9), the temperature sensor element 80 is located between the adjacent electrode segments 30. In this arrangement, each of the sensor elements 80 are threaded through the flexible body 32 between adjacent electrode segments 30. In the realization illustrated, the temperature sensing elements 80 comprise thermocouples When the sensor element 80 comprises a thermocouple, a 46 epoxy material, such as Master Bond Polymer System EP32HT (Master Bond Inc., Hackensack, New Jersey), encapsulates the thermocouple junction 84, securing it to the flexible body 32. Alternatively, the joint of thermocouples 84 can be covered with a thin layer of material poly (tetrafluoro-ethylene (PTFE). When use with a thickness of less than about 5.08 cm, these Materials have sufficient insulating properties to insulate  electrically the thermocouple junction 84 of the electrode segment associated 30, providing thermal conductive properties the enough to establish a conductive thermal contact with the electrode segment 30. The use of such materials will not be typically necessary when using thermistors, because the conventional thermistors are already encapsulated in an insulating material Electrical and thermal conductor.

In another alternative embodiment (as shown Fig. 10 and 11), the temperature sensor element 80 projects physically through an opening 86 in each segment of electrode 30. As in the embodiment shown in Fig. 24, the sensor elements 80 comprise thermocouples, and an epoxy material thermal and electrical non-conductive insulator encapsulating the junction of thermocouples 84, securing it inside the opening 86.

It should be noted that some sensor elements 80 they can be carried by electrode segment 30, while they can carrying other sensor elements 80 between the segments of the element 30. Many combinations of element arrangements sensors are possible, depending on the particular requirements of the ablation procedure.

II. Thermocouples temperature sensors for ablation cardiac A. Built-in reference thermocouple

Each temperature sensor element 80 can comprise a thermistor or a thermocouple. Thermocouples are preferred because, when compared to conventional thermistors current, a thermocouple is less expensive and has a lower profile, more compact. Still, as technology advances, thermistors Minor and other types of small temperature sensing elements they may appear available for use as described in This descriptive report.

Multiple thermocouples for sensors temperature conditions along an ablation element 10 They can be electrically coupled in various ways. Fig. 12A; 12B and 12C schematically show three embodiments representative.

In the preferred embodiment shown in Fig. 12A, multiple thermocouples (three of those shown and designate as T_ {1, 2, 3}) are located at, or near, the ablation electrodes, respectively, E1, E2 and E3. In the mode conventional, each thermocouple T 1, 2, 3 includes two wires electrically isolated 34 and 36 of dissimilar metals.

Various types of metals can be selected dissimilar to form the thermocouples T 1, 2, 3. For example, nickel-10% chrome can be electrically coupled be to constantane (forming a conventional Type E thermocouple) or to nickel-5% (aluminum silicon) (forming a thermocouple Type K conventional); iron can be electrically coupled to constantane (forming a conventional Type J thermocouple); Platinum-13% Rhodium can be electrically coupled to platinum (forming a conventional Type R thermocouple); Platinum-10% Rhodium can be electrically coupled to platinum (forming a conventional Type S thermocouple); or copper can be electrically coupled to constantane (forming a thermocouple Type T conventional).

In Fig. 12A, the wires 34 are made of copper and the wires 36 are of constantane, forming with this thermocouples of type T. Wires 34 and 36 are electrically isolated, except for the region 84 where they shed isolation and weld. Is region 84 is located at, or near, the associated electrode E1 / E2 / E3. This region 84 is encapsulated in an epoxy or PTFE material, as previously described, to electrically isolate the region 84 of the ablation electrode.

The measured voltage differences between the copper wire 34 and constantane wire 36 of each thermocouple T 1, 2, 3 vary with the temperature of the junction region 84. The voltage increases or decreases such as the temperature of the region 84, respectively, increases or decreases.

As Fig. 12A also shows, a single reference thermocouple T_ {REF} is electrically coupled in common to the three thermocouples T 1, 2, 3. The thermocouple of reference T_ {REF} is located in a region where there is a known temperature condition. This aspect will be described. Then in greater detail.

In Fig. 12A, the reference thermocouple T_ {REF} comprises a length of constantane wire 38, electrically isolated, locally stripped of insulation and electrically coupled in parallel to the constantane wire 36 of the three thermocouples T_ {1, 2, 3}.

The reference thermocouple T_ {REF} also Includes a length of 40 insulated copper wire, locally stripped of insulation and electrically coupled to the wire of constantano 38.

The junction region of the constantane wire 38 and the copper wire 40 is the thermocouple junction 42 of the reference thermocouple T_ {REF}. This union 42 is exposed to a known temperature condition. As the joining regions 84 between copper and constantane wire 34 and 36 of the others thermocouples T_ {1, 2, 3} (ie, regions 84), this region junction 42 of the reference thermocouple is also encapsulated in a epoxy or PTFE material that electrically insulates it from ablation electrodes

An external process element 92 is coupled electrically to thermocouples T_ {1, 2, 3} and T_ {REF}. The Particular details of this connection may vary and may be They will describe later in greater detail.

Process element 92 records the quantities of the voltage differences that exist between the wire 40 of copper of T_ {REF} and copper wire 34 of each of the thermocouples T_ {1, 2, 3} that are designated \ Delta_ {1, 2, 3} respectively (in Fig. 12A). The process element 92 derives of the voltage differences \ Delta_ {1, 2, 3} the condition of temperature for each thermocouple T 1, 2, 3, using the following equation:

\hskip1mm

_{N^{-}}TEMP

\hskip1mm

_{REF^{+}}\frac{\Delta V_{N}}{\alpha}TEMP

 \ hskip1mm 

TEM -

 \ hskip1mm 

REF {+}} \ frac {\ Delta V_ {N}} {\ alpha}

in the what:

TEMP_ {N} is the temperature condition noted by a thermocouple selected T_ {N (where N = 1, 2 or 3 in the Fig. 12A), whose magnitude is not known.

TEMP_ {REF} is the temperature condition noted by the reference thermocouple T_ {REF}, whose magnitude is known.

\ Delta_ {N} is the voltage difference between T_ {REF} copper wire 40 and copper wire 34 Thermocouple selected T N that is measured and known.

α is a known function (called Seebeck coefficient) that expresses the relationship between the voltage and temperature for the type of dissimilar metals used in the thermocouple

Additional details of this derivation method can be found in an available Omega publication, entitled Temperature , pages T-7 to T-18.

Preferably, the process element 92 includes a memory chip that contains a data table of input \ DeltaV_ {N} and match the expression \ DeltaV_ {N} /? to TEMP_N for the particular thermocouple type used. In this way, the process element 92 directly convert a measured voltage difference \ DeltaV_ {N} to a TEMP_ {N} temperature.

Fig. 12B schematically shows an arrangement alternative to electrically couple three thermocouples T_ {1, 2, 3} for use in an ablation element. In Fig. 12B, the Individual lengths of copper wire 40 are electrically coupled in the series with the constantane wire 36 of each thermocouple T 1, 2, 3, in the same manner described above. The individual junction regions 42 form three thermocouples reference individual, T_ {REF} 1,2,3, one for each thermocouple T 1, 2, 3. These joining regions 42 are each individually encapsulated within an epoxy or PTFE material, as already described. The three individual reference thermocouples that T_ {REF} 1,2,3 are normally exposed to the same condition known temperature.

As Fig. 12B shows, the differences in temperature related voltage Δ1, 2, 3} are measures between the copper wire 34 of a selected thermocouple T_ {1, 2, 3} and the copper wire 40 of your reference thermocouple associated, T_ {REF} 1,2,3

Fig. 12C schematically shows another arrangement alternative to electrically couple the three thermocouples, T_ {1, 2, 3}, for use in an ablation element. In Fig. 12C, a single length of copper wire 40 is electrically coupled in parallel with the constantane wire 36 of each thermocouple T_ {1, 2. 3}. The individual electrical junction regions 42 form three individual reference thermocouples T_ {REF} 1, 2, 3 one for each thermocouple T 1, 2, 3. As described above, the junction regions 42 are individually all encapsulated within of an epoxy or PTFE material. As in the embodiment shown in the Fig. 12B, the three individual reference thermocouples that they are normally exposed to T_ {REF} 1,2,3, the same condition known temperature.

As Fig. 12C shows, the differences in Temperature-related voltage, Δ1, 2, 3, are measures between the copper wire 34 of a selected thermocouple T_ {1, 2, 3} and the copper wire 40 of your reference thermocouple associated T_ {REF} 1,2,3

Conventional practice would locate the thermocouple reference reference T_ {REF} in the embodiment Fig. 12A, and the three individual reference thermocouples T_ {REF} 1,2,3 in the embodiments of Figs. 12B and 12C externally within the own process element 92 of temperature. In these arrangements (which can be used, if desired), the temperature condition known TEMP_ {REF} is the temperature at which the junction regions of the reference thermocouples. This condition of room temperature can be measured by a thermistor in the element of process 92. Alternatively, a circuit may be used conventional compensation.

The common reference thermocouple T_ {REF}, in the embodiment of Fig. 12A, and the three individual thermocouples of reference T_1,2,3, in Figures 12B and 12C, also they can be carried inside the handle 16 of the catheter probe 14. In this arrangement, the known temperature condition TEMP_ {REF} is the temperature in the handle 16 to which the regions are exposed junction 42 of the reference thermocouples. This condition of temperature can be measured by a thermistor in handle 16 (it is not shown), or using a conventional compensation circuit. Without However, in the preferred and illustrated embodiments, the thermocouple common reference T_ {REF} in the embodiment of Fig. 12A and the three reference thermocouples T_ {REF} 1, 2, 3 in Fig. 12B and 12C of the embodiments are incorporated into the body of the catheter 12 for exposure to blood flow in the body. In This preferred arrangement, all reference thermocouples are exposed to blood temperature, or being located in a chamber of the heart, or being located elsewhere in the vascular system of the patient where the catheter body rests. TEMP_ {REF} or TEMP_ {REF} (1, 2, 3)} with this are at, or near, 37 ° C

Figs. 13 and 14A show a preferred structural application of a reference thermocouple incorporated into the arrangement shown schematically in Fig. 12A.

As Fig. 13 shows, a coupler member 94 carried by the body of catheter 12 comprises the thermocouple of common reference T_ {REF}. The coupling member 94 is made of a biocompatible conductive thermal material, such as steel stainless or platinum

As Fig. 13 shows, the coupling member 94 is secured online, incorporated into catheter body 12 in a region spaced out of the ablation electrodes E1, E2, and E3 As described above, the coupling member 94 can be located inside a heart chamber (as Fig. 13), or elsewhere outside the ablation element 10 in the vascular system of the patient where the body 12 of the catheter.

If it is located inside the camera of the heart (as Fig. 13 shows), the coupling member 94 must to be spaced quite far, outside the electrode elements E1 / E2 / E3 so that the blood flow that is in contact with the coupler member 94 was not subject to the effects of heating by localized blood of the procedure ablation. In this situation, such as when the coupling member 94 is located further away from the heart chamber, the blood flow temperature that is in contact with the member coupler 94 will remain essentially constant at about 37 ° C during the ablation procedure.

As shown in detail in Fig. 14A, the member coupler 94 includes an inner hole 96 that is coated with an electrically insulating material 95. A ring 98 sits over a slot 100 inside the hole 96.

The coupler member 94 and the ring 98 can comprise a one piece assembly (as shown in Fig. 14A). In this arrangement, ring 98 includes a recess 102 to reduce its diameter, so that it can be pressed towards and adjusted by compression in place within slot 100. Alternatively, the member coupler 94 may comprise a two part body, separable to along groove 100, to allow ring placement 98. These arrangements allow electrical connections to the ring 98 are made out of member 94, before being placed in this.

In the embodiment shown in Fig. 14A, the Ring 98 is made of constantane metal. Ring 98 corresponds structurally to the length of the wire of constantan 38 shown in Fig. 12A so that the wires of constant 36 of the three thermocouples T_ {2, 3} are electrically coupled in parallel, as shown in Fig. 14A. The length of copper wire 40 (as shown in Fig. 12A) it is electrically coupled to ring 98 (as also shown in Fig. 14 TO).

This copper wire 40 and copper wire 34 of each thermocouple T_ {1, 2, 3} pass through the bore of the body of the catheter 12 at the external temperature of process element 92 (via the external connector 104) carried by the handle 16, as shown by the Fig. 1. Coupling member 94 and ring 98 with this serve as a reference thermocouple in line T_ {REF} common to thermocouples T1, 2, 3.

Fig. 14B shows an alternative embodiment for the coupling member 94 which is free of an inner ring 98. In Fig. 14B, the outer surface of the coupling member 94 It is coated with a 106, epoxy or TFE material, as previously It has already been described. Material 106 ties the catheter body 12 to the opposite ends of the coupling member 94. The material 106 also electrically isolates the coupling member 94 from the electrodes of ablation 30.

The coupler member 94 in Fig. 14B also includes an inner hole 96. The hole 96 has a region of its inner surface where a layer 108 of material is applied Constantano This layer 108 corresponds to the wire length of constantane 40 shown in Fig. 12A, to which the wire of constant 36 of the three thermocouples T_ {2, 3} is electrically coupled in parallel. The copper wire 40 for the reference thermocouple T_ {REF} also melts with the constantane of layer 108.

The constantane ring 98 in Fig. 14A and the constantane layer 108 in Fig. 14B collectively couple with the constantane wire 34 of each electrode thermocouple T1, 2, 3 to copper wire 40 of the reference thermocouple T_ {REF}. This simplifies the electrical connections inside of the inner regions, confined within the small diameter of the catheter body 12. Also, the constantane ring 98 and Layer 108 eliminates the need to pass the constantane wire 36 of each electrode thermocouple T1, 2, 3 across the entire catheter body length 12.

The temperature condition noted by the thermocouple built-in reference, T_ {REF}, is the temperature essentially constant of the thermally conducting blood flow  the coupling member 94, exposed to blood flow, The TEMP_ {REF} reference temperature is not subject to sudden change or variation, such as the external environment of air temperature This results in greater accuracy.

Figs. 15A and 15B show an embodiment alternative to use a single reference thermocouple. The wires of constantane 36 of the thermocouples T_ {1, 2, 3} are connected together by a solder or solder connection to the wire of constant 38 in a star configuration (shown in the Fig. 15A / B), although other configurations (such as a stair configuration). The reference thermocouple T_ {REF} it can then be put under a ring, just like the ones Thermocouples used to measure temperature. All wires of thermocouples are then thermally and electrically adjusted in a tube 114 to insulate them from RF wires (not shown). The Fig. 15B is the schematic representation of the connection of star of Fig. 15A.

Fig. 16A and 16B show an application Preferred structural structure of multiple reference thermocouples T_ {REF1,2,3}, incorporated and electrically coupled in the arrangement shown schematically in Fig. 12B. As the Fig. 16A, the three reference thermocouples, T_ {REF} 1,2,3, they are threaded individually through the body of catheter 12 and are encapsulate in a thermally and electrically insulating conductor in the epoxy bubble 110. Preferably, the thermocouples T_ {REF} 1,2,3 are closely spaced together.

As Fig. 16B shows, the number of wires entering process element 92 is reduced from six to four coupled to electrically couple the three wire of 40 copper associated with the reference thermocouples T_ {REF} 1,2,3 inside the handle 16 of the probe. This forms a single Copper wire 112 common to all reference thermocouples. The Common reference copper wire 112 and the other three wires Copper 34 thermocouples are connected T_ {1, 2, 3} to the element of process 92 (as shown in Fig. 16B). In this arrangement (as shows additional Fig. 16B), the Δ1,2,3 are measures between individual copper wires 34 for each thermocouple T 1, 2, 3 and common reference wire 112 of copper of the reference thermocouples T_ {REF} 1,2,3

The arrangement of multiple reference thermocouples T_ {REF} 1,2,3 incorporated in the arrangement shown schematically in Fig. 12C can be performed structurally using a coupler member 94 and ring 98, mounted in shape identical to that shown in Fig. 14, except that ring 98 is made of copper metal corresponding to common copper wire 40 shown in Fig. 12C. Alternatively, the multiple T_ {REF} 1,2,3 reference thermocouples, incorporated in the arrangement shown schematically in Fig. 12C, can be brought to out using the ring-free coupler member 94, structurally shown in Fig. 15, except that layer 108 inside the hole 96 the coupler is made of copper metal to correspond to the common copper wire 40 shown in Fig. 12C.

All thermocouple assemblies described in the Fig. 12A, B, and C require initialization before driving An ablation procedure. The temperature process element 92 goes through this initialization phase to compensate for voltage difference shifts Δ1, 2, 3 to the blood temperature

During the ablation procedure, the element process temperature 92 records the individual change in voltage differences Δ1, 2, 3. The element of temperature process 92 applies the associated displacement and then convert the change resulting from the differences of voltage Δ1, 2, 3 at temperature readings, using a table of input data, as already described.

The process element 92 of temperatures preferably displays the output of the conditions of temperatures measured along the ablation element 10. The multiple conditions of measured temperatures can also be used in a feedback control loop to control one's own ablation process This aspect of the invention will be described. Then in greater detail.

In the preferred embodiment, regardless the particular type of thermocouple used and the way it is electrically connected within the body of catheter 12, the 34/36 and 38/40 wires of the thermocouples are fitted in a tube 114 (see Fig. 16A} of thermal insulating material, such as polyimide Tube 114 thermally insulates thermocouple wires of other wires in the body that carries the ablation energy. Thus, thermocouple wires are thermally insulated from the heat that can be generated within the body of catheter 12 by the transfer of the energy of ablation to regions that emit energy to the extreme distal catheter body. The voltages indicating temperature, generated by thermocouples, so they are not altered by exposure from the thermocouple wire to this heat source inside the body of the catheter

B. Low profile compound thermocouple

Fig. 17 shows a thermocouple composed of low profile 116 that can thus be used in association with all types of flexible ablation elements 10. Thermocouple 116 comprises a thin, semi-flexible substrate 118 formed by a electrically insulating material, such as polyimide. In the Illustrated embodiment, the substrate 118 is tubular in shape. This of course other forms could be used.

Two electrical conductive paths 120 and 122 are extend along the surface of the substrate 118. The paths 120 and 122 can be applied by conventional techniques of spray or deposition coatings (IBAD) by ionic beam treatment. Alternatively, they could be embedded Small gauge wires of these materials of different metals inside the tubular substrate during extrusion or molding

Each path 120 and 122 comprises a material metallic of different electrical conductivity. Preferably, a path 120 is formed by applying copper, and the other path 122 is formed applying constantane.

The ends of the two paths merge electrically seals 120 and 122 in the substrate 118. In the preferred and illustrated embodiments, a band 124 of material of the metal of one of the paths 120 and 122 covers the ends of the paths 120 and 122, melting them electrically together. This band 124 forms a thermocouple junction on the surface of the substrate 118. Small, 126 and 128 gauge wires of metallic material corresponding are electrically coupled to opposite ends of paths 120 and 122.

A thin layer 130 of electrical insulation, exterior, is applied on paths 120 and 122 and the band of thermocouple 124 to complete the assembly of profile thermocouple 116 low.

Additional paths 120/122, band 124, and 126/128 wires can be applied to a single substrate 118 for form multiple thermocouple junctions on it.

As Fig. 18 shows, thermocouples semi-flexible 116 can be made small enough in its diameter to fit tightly within structure 10 below, or near, an ablation element 30. Alternatively, the thermocouples 116 can be made large enough in diameter as to fit tightly over flexible body 32, such as It also shows Fig. 18.

III. Control of cardiac ablation using multi temperature feedback

Fig. 19 shows, schematically, a 200 system for applying ablation energy by multiple emitters, at least in part, based on local conditions of temperatures, measured by multiple sensor elements 80.

In Fig. 19, the multiple sensor elements 80 comprise thermocouples 208, 209, and 210 individually associated with multiple emitters of ablation energy that comprise electrode regions 201, 202, and 203. The system 200 also includes a common reference thermocouple 211, ported within the coupling element 211 for exposure to the flow of blood, as previously described. Alternatively, they can use other types of temperature sensing elements, such as example, thermistors, fluoroptic sensors and sensors resistivity temperature, in which case it would not be required typically the reference sensor 211.

System 200 additionally includes a 219 electrode indifferent to mode operation unipolar

The emitters 201, 202, 203 of ablation energy may comprise rigid electrode segments 30, described previously. Alternatively, electrode regions 201, 202, 203 may comprise a flexible electrode, continuous or segmented, of tight wire or tape. It should be noted that system 200 can be used in association with any ablation element that use multiple ablation elements, independently powered.

System 200 includes a power source 217 of ablation. In Fig. 19, source 217 generates energy from radio frequency (RF). Source 217 is connected (through a output phase 216, isolated, conventional) to a series of power switches 214, one for each electrode region 201, 202, and 203. A connector 212 (carried by the probe handle) is electrically coupled to each region 201, 203, 203 of electrode a its own power switch 214 and other parts of the system 200.

System 200 also includes a microcontroller 231 coupled via an interface 230 to each power switch 214. The microcontroller 231 rotates a  given power switch 214 to the connected position, or of disconnected, to individually deliver RF power from the source 217 to electrode regions 201, 202 and 203. Energy of delivered RF flows from the respective electrode region 201, 202 and 203, through the tissue, to the indifferent electrode 219 that is connect to the return path of the isolated output phase 216.

The power switch configuration 214 and interface 230 may vary according to the type of ablation energy That is applied. Fig. 20 shows a representative application to use the energy of RF ablation.

In this application, each power switch 214 includes a 235 N-MOS power transistor and a 236 P-MOS power transistor, coupled between the respective region 201, 202, and 203 of electrode and the phase of isolated output 216 of power source 217.

A diode 233 carries the positive phase of RF energy of ablation to the electrode region. A diode 234 carries the phase Negative RF energy ablation to the electrode region. Resistors 237 and 238 polarize transistors N-MOS and P-MOS of power 235 and 236 in a conventional way.

The 230 interface for each power switch 214 includes two NPN transistors 239 and 240. The NPN emitter of the transistor 239 attaches to the transistor gate N-MOS 235 power. The transistor collector NPN 240 attaches to the transistor gate P-MOS 280 power.

The interface for each power switch 214 It also includes a 243 control bus, coupled to the microcontroller 231. Control bus 243 connects each power switch 214 to the digital ground (DGND) of microcontroller 231. The bus 243 control also includes a (+) power line (+ 5V) connected to the NPN 239 transistor manifold and a (-) line of power (-5V) connected to the emitter of the NPN transistor interface 240.

The 243 control bus for each power switch power 214 additionally includes an E_ {SEL} line. Base of transistor NPN 239 is coupled to line E_ {SEL} of the bus control 243. The base of NPN 240 transistor is also coupled to line E_ {SEL} of control bus 243 via the Zener diode 241 and a resistor 232. The line E_ {SEL} is connected to the cathode of the Zener diode 241 through resistor 232. Zener diode 241 is selected so that the NPN 240 transistor turns on when E_ {SEL} exceeds approximately 3 volts (which, for the particular embodiment shown, is logical 1).

It should be appreciated that interface 230 can be designed to deal with other logical level standards. In the particular realization, the levels are designed to manage conventional levels of TTL (by the acronym of its expression English, Transistor Transfer Logic, transfer logic transistors).

Microcontroller 231 puts E_ {SEL} on the bus control 243 to logic 1 or logic 0. In logic 1, the gate of the transistor N-MOS 235 connects to line (+) 5 volts through the NPN 239 transistor. Similarly, the P-MOS 236 transistor gate connects to the line (-) 5 volts through NPN 240 transistor. This conditions the power transistors 235 and 236 to direct the source voltage of RF 217 to the associated region of electrode. Power switch 214 is in position "connected".

When microcontroller 231 sets E_ {SEL} to logic 0, no current flows through the NPN transistors 239 and 240. This conditions the power transistors 235 and 236 to block the conduction of RF voltage to the region electrode associated. Power switch 214 is "disconnected".

System 200 (see Fig. 19) additionally includes two analog multiplexers (MUX) 224 and 225. The multiplexers 224 and 225 receive the voltage input of each thermocouple 208, 209, 210 and 211. Microcontroller 231 controls both  multiplexers 224 and 225 to select the voltage inputs of the multiple temperature sensors of thermocouples 208, 209, 210, and 211.

The voltage inputs of thermocouples 208, 209, 210 and 211 are sent to the front end signal that It conditions the electronic system. The inputs are amplified by the differential amplifier 226 that reads the voltage differences between the copper wires of thermocouples 208/209/210 and that of the reference thermocouple 211. The voltage differences are conditioned by element 227 and converted to codes digital by analog / digital converter 228. The table of Data 229 converts digital codes to temperature codes. The temperature codes are read by microcontroller 231.

Microcontroller 231 compares the codes of temperature for each thermocouple 208, 209, and 210 with the criteria preset to generate feedback signals. The Preset criteria is entered through an interface of user 232. These feedback signals control the power switches 214, via interface 230, passing the electrodes 201, 202, and 203 from connected to disconnected.

The other multiplexer 225 connects the thermocouples 208, 209, 210, and 211, selected by microcontroller 231, a a temperature controller 215. The 215 controller of temperature also includes the front end signal that conditions the electronic system, as already described with reference to elements 226, 227, 228, and 229. This system electronic converts voltage differences between wires Copper thermocouples 208/209/210 and the reference thermocouple 211 at temperature codes. The temperature codes are read by the controller and compare with the preset criteria for Generate feedback signals. These signals feedback control the amplitude of the voltage (or current) generated by source 217 that must be delivered to the electrodes 201, 202, and 203.

Based on the feedback signals of the microcontroller 231 and controller temperature 215, the system 200 distributes power to multiple regions electrodes 201, 202, and 203 to establish and maintain a uniform temperature distribution throughout the element of ablation. In this way, system 200 achieves training Safe and effective injury caused by multiple emitters of ablation energy.

System 200 can control the delivery of Ablation energy in different ways. Will now be described Several representative modes.

Individual amplitudes / collective load cycle

Electrode regions 201, 202, and 203 are symbolically designate E (J), where J represents a given region of electrode (J = 1 to N).

As described above, each region E (J) electrode has at least one temperature sensing element 208, 209, and 210 to be designated S (J, K), where J represents the electrode region and K represents the number of elements temperature sensors in each electrode region (K = 1 a M).

In this mode (see Fig. 21), the microcontroller 316 operates switch interface 230 power to deliver RF power from source 217 in multiple 1 / N load cycle pulses.

With pulsed power delivery, the quantity of power (P {E (j)} carried to each individual region of electrode E (J) is expressed as follows:

E.g)} - AMP_ {E (j) 2} \ X \ (CYCLE \ DE \ LOAD) E (J)

where:

AMP_ {E (j)} is the amplitude of the voltage of RF carried to electrode region E (J), and (CYCLE OF LOAD) E (J) is the pulse charge cycle, expressed as follows:

\hskip1mm

/

\hskip1mm

(TON_{E(J)} - TOFF_{E \ (J)})(CYCLE \ OF \ LOAD) _ {E \ (J)} = TON_ {E (J)}

 \ hskip1mm 

/

 \ hskip1mm 

(TON_ {E (J)} - TOFF_ {E \ (J)})

where:

TON_ {E (J)} is the time that the region of electrodes E (J) emits energy during each period of the pulse,

TOFF_ {E (J)} is the time that the region of electrodes E (J) does not emit energy during each period of pulse.

The expression TON_ {E (J)} + TOFF_ {E \ (J)} represents the pulse period for each electrode region E (J).

In this mode, microcontroller 231 sets a collective load cycle ((LOAD CYCLE) _ E \ (J)}) of 1 / N for each electrode region (N is equal to the number of electrode regions).

Microcontroller 231 can send a sequence of successive power pulses to adjacent regions of electrodes so that the end of the pulse charge cycle previous overlap slightly with the beginning of the charging cycle for the next pulse. This overlap in pulse load cycles ensures that source 217 applies power continuously, without the interruption periods caused by open circuits during the exchange of pulses between successive regions of electrodes

In this mode, the temperature controller 215 makes individual adjustments of the RF voltage amplitude for each electrode region (AMP_ {E (j)}), changing individually with this the power P_ {E (j)} of energy of ablation carried during the loading cycle to each region of electrodes, as controlled by microcontroller 231.

In this mode, microcontroller 231 performs cycles in the sampling periods for data acquisition successive During each sampling period, the microcontroller 231 selects the individual sensors S (J, K), and the voltage differences are read by controller 215 (through of MUX 225) and converted to temperature codes TEMP (J).

When there is more than one sensor element associated with a given electrode region, controller 215 records all the measured temperatures for the given electrode region and select among them the highest measured temperature, which constitutes TEMP (J). The temperature sensing element that maintains the highest measured temperature in an electrode region given is the one in the most intimate contact with the tissue of the heart. The lowest measured temperatures of the other elements sensors in the given electrode region indicate that the others sensor elements are not in such intimate contact, and are exposed in change to convective cooling in blood flow.

In this mode, controller 215 compares the TEMP temperature (J) locally measured at each electrode E (J) during each data acquisition period with a preset temperature TEMP_ {SET}, which is set by the doctor. Based on this comparison, controller 215 varies the AMP_ {E (j)} amplitude of the RF voltage delivered to the electrode region E (J), while microcontroller 231 maintains (LOAD CYCLE) E \ (J)} for that region of the electrode and all other electrode regions, so set and maintain TEMP (J) at the preset temperature TEMP_ {SET}.

The preset TEMP_ {SET} temperature can vary according to the doctor's judgment and empirical data. It is believed than a representative preset temperature for ablation cardiac is in the range from 40ºC to 95ºC, with 70ºC being a preferred representative value.

The way in which controller 215 governs AMP_ {E (j)} can incorporate proportional methods of control, proportional integral derivative control methods (PID, by the acronym of its English expression, Proportional Integral Derivative), or incorporate confusing logic control methods.

For example, using control methods proportional, if the temperature measured by the first element sensor is TEMP (1)> TEMP_ {SET}, the control signal individually generated by controller 215 reduces the amplitude AMP_ {E (1)} of the RF voltage applied to the first region of electrode E (1), while microcontroller 231 maintains the same collective load cycle (CYCLE OF LOAD) E (1) for the first electrode region E (1). If the temperature measured by the second element sensor is TEMP (2) <TEMP_ {SET}, the control signal of the controller 215 increases the AMP_ {E (2)} pulse width applied to the second region of electrode E (2), while the microcontroller 231 maintains the collective load cycle (CYCLE OF LOAD) E (2) for the second electrode region E (2) equal to (LOAD CYCLE) E (1), and so on successively. If the temperature measured by a given sensor element is at the preset temperature TEMP_ {SET}, no change in the amplitude of the RF voltage for the associated region of electrode.

Controller 215 continuously processes the voltage difference inputs during successive periods of data acquisition to adjust individually AMP_ {E (j)} for each electrode region E (J), while microcontroller 231 maintains the same cycle of collective load for all regions E (J) of electrode. From In this way, the mode maintains a desired uniformity of temperatures throughout the length of the element of ablation.

Using a differential control technique proportional integral, the 215 controller takes into account not only the instantaneous changes that occur in a sampling period given, but also the changes that have occurred in the periods previous sampling and the proportion to which these changes are varying over time. Thus, using a PID control technique, the 215 controller will respond differently to a big difference snapshot given proportionally between TEMP (J) and TEMP_ {SET}, depending on whether the difference is getting bigger or smaller, comparing them with previous instantaneous differences, and if the speed at which the difference is changing from previous sampling periods is increasing or is decreasing

Collective amplitudes / individual load cycles

In this feedback mode (see Fig. 22), controller 215 governs source 217 to control collectively the amplitude AMP_ {E (j)} of RF voltage for all electrode regions based on local temperature plus low TEMP_ {SMIN} measured. At the same time, in this mode of feedback, microcontroller 231 individually alters the power driven to the electrode regions, where measured temperatures are higher than TEMP_ {SMIN}, due to the setting of the charge cycle (LOAD CYCLE) E {(J)} of these electrode regions

In this mode, as in the previous mode, the microcontroller 231 separates the power into multiple pulses. Initially, each pulse has the same charge cycle ((CYCLE OF LOAD) E ((J)) of 1 / N. As in the previous mode, the application of successive RF pulses to adjacent regions of electrodes can be timed to overlap so that the source 318 continuously apply power to electrode regions E (J).

Controller 215 performs cycles in periods successive data acquisition to read the sensor temperature sequentially for each sensor element of TEMP (J). When there are multiple sensor elements associated with each region of electrodes, the controller 215 records all temperature measurements for the particular electrode and select among these the highest measured temperature that will be TEMP (J).

In this mode, controller 215 compares, during each period of data acquisition, individual temperatures TEMP measurements (J) with the preset temperature TEMP_ {SET}. The 215 controller also selects the measured temperature plus low TEMP_ {SMIN}. Controller 215 adjusts AMP_ {E (j)} to keep TEMP_ {SMIN} = TEMP_ {SET}, using the techniques of proportional control, PID, or confusing logic. At the same time, the microcontroller 231 adjusts the (LOAD CYCLE) E (J)} of the electrode regions where TEMP (J)> TEMP_ {SMIN} to hold TEMP (J) = TEMP_ {SET}

For example, using only proportional techniques control, if TEMP_ {SMIN} <TEMP_ {SET}, controller 215 collectively increases the amplitude of the RF voltage of all electrode regions, based on the difference between TEMP_ {SMIN} and TEMP_ {SET} (\ DeltaTEMP_ {SMIN} {/ SET}), until TEMP_ {SMIN}> TEMP_ {SET}.

During this time (when TEMP_ {SMIN} remains below TEMP_ {SET}), microcontroller 231 also controls the application of power to the other regions E (J) of electrodes, where the local temperature TEMP (J) measured is above TEMP_ {SMIN}, as follow:

 If TEMP (J) < TEMP_ {SET}, microcontroller 231 increases the charge cycle of power applied to the electrode region E (J) in the RF voltage amplitude set by \ DeltaTEMP_ {SMIN} _{/SET}.

 If TEMP (J)> TEMP_ {SET}, microcontroller 231 decreases the charge cycle of power applied to the electrode region E (J) in the RF voltage amplitude set by ΔTEMP_ {SMIN} _{/SET}

 If TEMP_ {S (N)} = TEMP_ {SET}, microcontroller 231 maintains the charge cycle for the given region of electrode E (N) in the amplitude of RF voltage set by \ DeltaTEMP_ {SMIN} _{/SET}.

When TEMP_ {SMIN}> TEMP_ {SET}, the 215 controller collectively reduces the RF voltage amplitude Delivered to all electrode regions. When TEMP_ {SMIN} = TEMP_ {SET}, controller 215 maintains the voltage amplitude of RF then established, which is collectively delivered to All electrode regions.

Temperature control with hysteresis

In this mode (see Fig. 23), as in the previous modes, system 200 performs cycles in periods successive data acquisition to sequentially record the temperature measured by the TEMP sensor elements (J) for electrode regions E (J). As before, when there is multiple sensor elements associated with each region of electrodes, system 200 records all measured temperatures for the particular electrode region and select among them the highest measured temperature that becomes TEMP (J).

In this mode, microcontroller 231 compares locally the measured temperature of each electrode region TEMP (J) during each period of data acquisition with the TEMP_ {HITHRESH} high and low threshold temperatures and TEMP_ {LOWTHRESH} where

TEMP_ {HITHRESH} = TEMP_ {SET} + INCR

where

TEMP_ {LOWTHRESH} = TEMP_ {SET} - INCR

TEMP_ {SET} is the default temperature, and INCR It is a preselected increase.

When operating in this mode, the microcontroller 231 operates the 230 power switch interface to disconnect a given region E (J) of electrodes, when the temperature local measurement of that electrode region is TEMP (J)> TEMP_ {HITHRESH}. Microcontroller 231 maintains the region of electrode disconnected until local temperature measured TEMP (J) falls below TEMP_ {LOWTHRESH}. The microcontroller 231 connects a given electrode region E (J) and supplies power at a voltage amplitude selected when the measured local temperature of that region of electrode be TEMP (J) <TEMP_ {LOWTHRESH}

The values for TEMP_ {SET} and INCR can vary according to the doctor's judgment and empirical data. Like before exposed, it is believed that a representative value for TEMP_ {SET} it is in the range between 40 ° C and 95 ° C, with a preferred value of 70 ° C A representative value of INCR is believed to remain in the range from 2ºC to 80ºC, with a representative value preferably around 5 ° C.

In this application, controller 215 sets a constant RF voltage amplitude high enough of so that during the hysteresis the conditions of desired temperature Alternatively, controller 215 may have the ability to adjust the voltage in the event that the TEMP_ {SMIN} coldest measured temperature decrease below a lower limit selected below TEMP_ {LOWTHRESH}, or in the case that the longest load cycle exceeds a value predetermined. It should be appreciated that there are other ways to adjust and maintain the amplitude while the control method is carried out with hysteresis

Differential temperature deactivation

In this mode (see Fig. 24), the controller of temperature 215 selects at the end of each acquisition phase of data the measured temperature that is the largest for that phase (TEMP_ {SMAX}). The 215 temperature controller also select for that phase the measured temperature that is the lowest (TEMP_ {SMlN}).

The 215 controller compares the temperature more hot selected TEMP_ {MAX} measurement with a temperature High preset selected TEMP_ {HISET} .The comparison generates a control signal that collectively adjusts the amplitude of the RF voltage for all electrodes using the techniques of proportional control, PID or confusing logic.

In a control application scheme proportional:

(i)

If TEMP_ {SMAX} > TEMP_ {HISET}, the control signal decreases collectively The amplitude of the RF voltage delivered to all regions of electrodes

(ii)

If TEMP_ {SMAX} <TEMP_ {HISET}, the control signal collectively increases the RF voltage amplitude delivered to all regions of electrodes

(iii)

If TEMP_ {SMAX} = TEMP_ {HISET}, no change is made in the amplitude of the RF voltage delivered to all electrode regions.

It should be appreciated that the temperature controller 215 can select any one of the amplitude control measured temperatures TEMP_ {SMAX}, TEMP_ {SMIN}, or temperatures between these, and this temperature condition must be compared with a pre-selected temperature condition.

Working in tandem with the control function of amplitude of temperature controller 215, microcontroller 231 governs the delivery of power to the electrode regions in based on the difference between a given local temperature TEMP (J) and TEMP_ {SMIN}. This application computes the difference between the measured local temperature TEMP (J) and TEMP_ {SMIN} and compare this difference with a preset temperature difference selected \ DeltaTEMP_ {SMIN} {/ SET}. The comparison generates a control signal that governs the delivery of power to the electrode regions

If the measured local temperature of TEMP (J) for a given electrode region E (J) exceeds the TEMP_ {SMIN} lowest measured temperature in as much as, or more than, ΔTEMP_ {SMIN} {/ SET} (that is, if TEMP (J) - TEMP_ {SMIN} \ geq \ DeltaTEMP_ {SMIN} {/ SET}, the microcontroller 231 disconnects the given electrode region E (J). The microcontroller 231 reconnects the electrode given E (J) when TEMP (J) - TEMP_ {SMIN} < ΔTEMP_ {SMIN} / SET}.

Alternatively (see Fig. 25), instead of compare TEMP (J) and TEMP_ {SMIN}, microcontroller 231 You can compare TEMP and TEMP_ {SMIN}. When the difference between TEMP_ {SMAX} and TEMP_ {SMIN} match or exceed a preset amount  \ DeltaTEMP_ {SET}, controller 231 disconnects all electrode regions, except the electrode region where TEMP_ {SMIN} exists. Controller 231 reconnects these electrode regions when the temperature difference between TEMP_ {SMAX} and TEMP_ {SMIN} BE less than ΔTEMP_ {SET}.

Some of the control schemes, based on the temperatures described above, alter the power by adjusting The amplitude of the RF voltage. It should be noted that, alternatively, the power can be altered by adjusting the amplitude RF current Therefore, the amount that AMP_ {E (J)} used in this specification can mean both the amplitude of the RF voltage or the current RF amplitude

III. Selecting among multiple sensor elements of temperature

As previously described, a given region electrode can have more than one temperature sensing element associated with her. In previously ablation control modes described, controller 215 records all temperatures measurements for the given electrode region and select among them the highest measured temperature, which will constitute TEMP (J). There is Alternative ways to make this selection.

Deriving the hottest temperature

Due to the heat exchange between the tissue and the electrode region, the temperature sensing elements do not They can measure exactly the maximum temperature in the region. This is because the hottest temperature region occurs under the tissue surface at a depth from about 0.5 up to 2.0 mm, where the energy emitted by the electrode region (and the associated sensor element) is in contact with the tissue. If the power is applied to heat the tissue too quickly, the maximum actual tissue temperature in this subsurface region can exceed 100 ° C and can lead to the drying of the tissue.

Fig. 26 shows an application of a network predictive neural 300 that receives as inputs the temperatures S (J, K) measured by multiple sensor elements of each electrode region where J represents a given electrode region (J = 1 to N) and K represents the number of sensor elements of temperature in each electrode region (K = 1 to M). The predictor 300 outputs at a temperature of the tissue region, the most hot, T_ {MAXPRED (t)}. The 215 driver and microcontroller 231 derive the amplitude and control signals from collective load cycle based on T_ {MAXPRED (t)}, of the same way already described using TEMP (J).

The predictor 300 uses a two-layer neural network, although the most hidden layers could be used. As shown in Fig. 26, the predictor 300 includes a first and second layers hidden and four neurons, designated N (L, X), where L identify layer 1 or 2 and X identify a neuron in that layer. The First layer (L = 1) has three neurons (X = 1 to 3), as follows N (1,1); N (1,2), and N (1,3) The second layer (L = 2) comprises an output neuron (X = 1), designated N (2,1)

The readings of multiple temperature sensing elements, of which only two are shown, - -TS1 (n) and TS2
(n) - -, for purposes of illustration, N (1,1), N (1,2) and N (1,3) of the first layer are weighed and entered into each neuron. Fig. 26 represents the weights as W L (k, N), where L = 1; k is the order of the input sensor, and N is the input neuron number 1, 2, or 3 of the first layer.

The exit neuron N (2,1) of the second layer receives as input the heavy outputs of neurons N (1,1); N (1,2); and N (1,3). Fig. 26 represents the output weights such as W L (0,, X), where L = 2; 0 is the output of neuron 1, 2, or 3 of the first layer; and X is the number of Neuron entrance of the second layer. Based on these entries heavy, the exit neuron N (2,1) predicts T_ {MAXPRED (t)}

The predictor 300 must be trained in a game known data containing the temperature of the elements TS1 and TS2 sensors and the hottest region temperature that It has been experimentally acquired previously. For example, using a backward propagation model, the predictor 300 can train to predict the hottest known temperature of the data flow with the mean square error. Once the phase of training is completed, the predictor 300 can be used to predict T_ {MAXPRED (t)}.

Other types of techniques can be used. data processing to derive T_ {MAXPRED (t)}. By example, see U.S. Patent No. 5906614 entitled "Tissue Heating and Ablation Systems and Methods Using Predicted Temperature for Monitoring and Control ".

Preferred and illustrated embodiments use a digital processing controlled by a computer to analyze the information and generate feedback signals.

It should be noted that other control circuits logical that they use micro-switches, gates AND / OR, inverters, analog circuits, and the like are equivalent to microprocessor controlled techniques shown in the preferred embodiments.

Claims (19)

1. A system for tissue ablation body, which includes:

Multiple emitters (30, 201, 202, 203) of ablation energy; at least one sensor element of temperature (80, 208, 209, 210) in each energy emitter for Measure the temperature of the energy emitter.

A power controller (230) that couples an ablation energy source with each emitter of energy to drive the ablation energy to the emitters of energy

A process element (215, 231) to periodically read the temperature measured by each temperature sensor element and select one of the temperatures measures based on the pre-established criteria for comparison with a desired temperature to generate a signal.

A temperature controller (215, 231) coupled to the power controller to control the conduction of ablation energy to the energy emitters in signal base.

2. A system according to claim 1, in the what:

Power controller (230) couples each energy emitter (30, 201, 202, 203) with the ablation energy source to conduct ablation energy individually towards each energy emitter in a sequence of power pulses, each power pulse having a cycle of load and an amplitude, in which the power delivered to each emitter Energy for tissue ablation is expressed as follows:

POWER - WIDTH2 \ x \ (CYCLE \ LOAD)

The process element (215, 231) is adapted to compare the temperature measured by each temperature sensor element with a desired temperature and is adapted to individually generate a signal for each emitter of energy based on the comparison, at which the desired temperature It is set for all issuers.

Temperature controller (215, 231) individually the power pulse varies for each energy emitter based on the signal for that energy emitter to in order to maintain temperatures in all energy emitters essentially at the desired temperature during the ablation of the tissue.

3. A system according to claim 2, in which: The temperature controller (215, 231) varies the power pulse by individually varying the pulse width of power based on the signal for that energy emitter (30, 201, 202, 203), while maintaining the charge cycle of the pulses of essentially the same power for all emitters of Energy. 4. A system according to claim 3, in the that the charge cycle is 1 / N, in which N is the number of emitters of energy (30, 201, 202, 203). 5. A system according to claim 3, in the that the temperature controller (215) varies the amplitude, be varying the voltage or current. 6. A system according to claim 3, in the that the temperature controller (231) individually disconnects an energy emitter (30, 201, 202, 203) when the temperature measured at the energy emitter equals or exceeds the temperature desired in a predetermined amount and individually connect the energy emitter when the temperature measured in the emitter of energy is less than a desired temperature in an amount default 7. A system according to claim 2, in the that the temperature controller (215, 231) varies the pulse of power by individually varying the charge cycle of the emitter of energy (30, 201, 202, 203) based on the signal for that emitter of energy, while maintaining the amplitude of the power pulses essentially the same for all energy emitters. 8. A system according to claim 7, in the that the temperature controller (231) disconnects individually an energy emitter (30, 201, 202, 203) when the temperature measured at the energy emitter equals or exceeds a temperature desired in a predetermined amount and individually connect the energy emitter when the temperature measured in the emitter of energy is less than the desired temperature in an amount default 9. A system according to claim 2, in the that the temperature controller (215, 231) varies the pulse of power by individually varying both the charge cycle and the amplitude of the power pulse for each energy emitter (30, 201,  202, 203) based on the signal for that energy emitter. 10. A system according to claim 9, in the that the temperature controller (231) individually disconnects an energy emitter (30, 201, 202, 203) when the temperature measured at the energy emitter equals or exceeds the temperature desired in a predetermined amount and individually connect the energy emitter when the temperature measured in the emitter of energy is less than the desired temperature in an amount default 11. A system according to claim 9, in the that the temperature controller (215) varies the amplitude by varying Be it the voltage or the current. 12. A system according to claim 1, in the what:

Each energy emitter (30, 201, 202, 203) defines a zone E (J) that emits Energy.

The temperature measured in each zone E (J) that emits energy is designated as TEMP (J)

Power controller (230) includes a switch element (214) to drive the energy of ablation individually towards each zone E (J) in a power pulse that has a charge cycle (CYCLE OF LOAD) E (J) and an amplitude AMP_E (j)}, setting AMP_ {E (j)} to be essentially the same for all E (J), in which the power P_ {E (j)} Delivered to each zone E (J) is expressed as follows:

P_ {E (J)} \ sim AMP_ {E (J) 2} \ x \ (CYCLE \ DE \ LOAD) E (J)

The process element (215) includes means to identify the temperature condition of lowest TEMP_ {SMIN} reading of all TEMP (J) and media to compare the lowest reading temperature condition TEMP_ {SMIN} with the desired temperature condition, designated TEMP_ {SET}, and the signal is based on the comparison; Y

the temperature controller (215) is adapted to vary the power pulse to each zone E (J) based on the signal by varying AMP_ {E (j)} to all E (J) to keep TEMP_ {SMIN} = TEMP_ {SET}.

13. A system according to claim 1, in the what:

Each energy emitter (30, 201, 202, 203) defines a zone E (J) that emits Energy.

The temperature measured in each zone E (J) that emits energy is designated as TEMP (J).

The power controller (230) includes a switch element (214) to conduct the ablation energy individually to each zone E (J) in a power pulse that has a charge cycle (LOAD CYCLE

 \ hbox {) E (J)}} 

and an amplitude AMP_ {E (j)}, AMP_ {E (j)} being set to be essentially the same for all E (J), in which the power P_ {E (j)} delivered to each zone E ( J) is expressed as follows:

P_ {E (j)} \ sim AMP_ {E (j) 2} \ x \ (CYCLE \ DE \ LOAD) E (J)

The process element (215) includes means to identify the temperature condition of lowest TEMP_ {SMIN} reading of all TEMP (J) and media to compare the lowest reading temperature condition TEMP_ {SMIN} with the desired temperature condition, designated like TEMP_ {SET}, and the signal is based on the comparison.

Temperature controller (215, 231) is adapted to vary the power pulse at each zone E (J) based on the signal varying AMP_ {E (j)} for all E (J) to keep TEMP_ {SMIN} = TEMP_ {SET} while the (CYCLE OF LOAD) E (J) of each zone E (J), in which TEMP (J)> TEMP_ {SMIN} to hold TEMP (J) = TEMP_ {SET} for each such zone.

14. A system according to claim 1, in the that the selected temperature between the measured temperatures It comprises the highest of the measured temperatures. 15. A system according to claim 1, in the that the power controller (230) couples each power emitter (30, 201, 202, 203) with the ablation power source for conduct the ablation energy individually to each emitter of  energy in a sequence of power pulses, each pulse having of power a load cycle and an amplitude, in which the power delivered to each energy emitter for ablation of the tissue is expressed as follows: POWER \ sim AMPLITUDE2 \ x \ (CYCLE \ DE \ LOAD)

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and the temperature controller (215, 231) is adapted to vary the power pulses to the emitters of energy based on the signal. 16. A system according to claim 1, in the what,

Each energy emitter (30, 201, 202, 203) defines a zone E (J) that emits Energy.

The temperature measured in each zone E (J) that emits energy is designated as TEMP (J).

Power controller (230) includes a switch element (214) to drive the energy of ablation individually towards each zone E (J) in a power pulse that has a charge cycle (CYCLE OF LOAD) E (j) and an amplitude AMP_E (j), in the power P_ {E (j)} delivered to each zone E (J) is expressed as follows:

P_ {E (j)} \ sim AMP (j) 2} \ x \ (CYCLE \ DE \ LOAD) E (J)

The process element (231) includes means to compare each temperature condition of TEMP (J) reading with a prescribed low threshold condition of TEMP_ {LOWTHRESH} temperature and a prescribed threshold condition TEMP_ {HITHRESH} high temperature.

Temperature controller (231); is adapted to disconnect a given zone E (J) when TEMP (J) for that zone is> TEMP_ {HITHRESH} and is adapted to connect the given area E (J) when TEMP (J) for that zone is <TEMP_ {LOWTHRESH}.

17. A system according to claim 1, in the what:

There are at least two temperature sensing elements (80, 208, 209, 210) in each energy emitter (30, 201, 202, 203) to measure the temperature in The energy emitter.

The process element (215) is adapted to periodically read the temperatures measured by each of the temperature sensing elements for each emitter of energy, and to select for each energy emitter the hottest temperature of the measured temperatures, to compare the hottest of temperatures for each energy emitter with the desired temperature, and is adapted to generate individually a signal for each energy emitter based on the comparison, in which the desired temperature is set to All issuers

Temperature controller (215) is adapted to individually control the driving of energy to each energy emitter, based on the signal for that emitter of energy, so that during tissue ablation the hottest temperature in all energy emitters is keep essentially at the desired temperature.

18. A system according to claim 17, in the that the power controller (230) individually couples each energy emitter (30, 201, 202, 203) to the power source of ablation to drive the energy of ablation individually towards each energy emitter in a sequence of power pulses, each power pulse having a charge cycle and an amplitude, in which the power delivered to each energy emitter for the Tissue ablation is expressed as follows: POWER \ sim AMPLITUDE2 \ x \ (CYCLE \ DE \ LOAD) and the temperature controller (215) is adapted to individually vary the power pulse towards each energy emitter based on the signal for that energy emitter so that the hottest temperature in all emitters of energy is essentially kept at the temperature desired. 19. A system according to claim 1, in the what:

There are at least two elements temperature sensors (80, 208, 209, 210) in each emitter of energy (30, 201, 202, 203) to measure the temperature in the emitter of energy

Power controller (230) individually couples each energy emitter with the source of ablation energy to individually conduct the energy of ablation to each energy emitter in a sequence of pulses of energy, each power pulse having a charge cycle and a amplitude, in which the power delivered to each energy emitter for tissue ablation it is expressed in the manner next:

Power \ sim WIDTH2 \  x \ (CYCLE \ DE \ LOAD)

The process element (215, 231) is adapted to periodically observe temperatures measurements for each of the temperature sensing elements to each energy emitter for each energy emitter to predict the warmer tissue temperature, to compare the temperature warmest predicted for each energy emitter with the temperature  desired, and is adapted to individually generate a signal for each energy emitter based on the comparison, in what the Desired temperature is set for all emitters.

And the controller of temperature (215, 231) is adapted to vary individually the power pulse to each energy emitter based on the signal for that energy emitter so that during the ablation of the tissue the warmest temperature predicted in all emitters of energy essentially stay at the temperature desired.